Improve Aircraft Structure Safety by Reinforcing the Critical Location Using Structural Health Monitoring

Fatigue remains the predominant mode of failure in the aviation industry, accounting for 55% of the incidents occurring. While the current industry practice relies on attaching a doubler on one side to address fatigue crack growth, the induced bending stress due to the neutral axis offset can be counterproductive and accelerate the crack growth rate. In this work, the fatigue crack growth of an airplane panel was examined for different configurations including one and two-sided doublers. With the aim of producing a reliable and simplified model capturing the fatigue crack growth mechanism. The results showed that while one-sided doublers reduce the operational lifetime by 38%, using a two-sided doubler, it increases by 86%. Analyzing the peak von-Mises stress across the different configurations, the one-sided doubler configuration had the highest stress due to bending, while the two-sided configuration mitigated and addressed this design problem. The work motivates further development in studying the application of two-sided doublers as a new industry standard to significantly extend the operational lifetime of an aircraft while reducing the operating costs of aviation companies.